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Dive into the research topics where Giovanni Pennelli is active.

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Featured researches published by Giovanni Pennelli.


Journal of The Optical Society of America B-optical Physics | 2002

Optical discrete solitons in waveguide arrays. I. Soliton formation

H. S. Eisenberg; Roberto Morandotti; Yaron Silberberg; J.M. Arnold; Giovanni Pennelli; J. S. Aitchison

We investigate the generation of discrete spatial solitons in arrays of coupled waveguides. Light was launched into the center of the array, and different beam sizes and array geometries were tested. At low power, the propagating field spreads as it couples to more waveguides. When the intensity is increased, localization is observed around the input waveguides, leading to the formation of a discrete soliton. For wide input beams, exciting a few waveguides, soliton splitting, which is due to instability induced by multiphoton absorption, is observed. All of these effects are described well by a coupled-mode formalism.


IEEE Journal of Selected Topics in Quantum Electronics | 1999

Design and construction of an optoelectronic crossbar switch containing a terabit per second free-space optical interconnect

A. C. Walker; Marc Phillipe Yves Desmulliez; M. G. Forbes; S.J. Fancey; Gerald S. Buller; Mohammad R. Taghizadeh; Julian A. B. Dines; C.R. Stanley; Giovanni Pennelli; Adam R Boyd; Paul Horan; Declan Byrne; J. Hegarty; Sven Eitel; Hans Peter Gauggel; K. H. Gulden; Alain Gauthier; Philippe Benabes; Jean-Louis Gutzwiller; Michel Goetz

The completed detailed design and initial phases of construction of an optoelectronic crossbar demonstrator are presented. The experimental system uses hybrid very large scale integrated optoelectronics technology whereby InGaAs-based detectors and modulators are flip-chip bonded onto silicon integrated circuits. The system aims to demonstrate a 1-Tb/s aggregate data input/output to a single chip by means of free-space optics.


Beilstein Journal of Nanotechnology | 2014

Review of nanostructured devices for thermoelectric applications.

Giovanni Pennelli

Summary A big research effort is currently dedicated to the development of thermoelectric devices capable of a direct thermal-to-electrical energy conversion, aiming at efficiencies as high as possible. These devices are very attractive for many applications in the fields of energy recovery and green energy harvesting. In this paper, after a quick summary of the fundamental principles of thermoelectricity, the main characteristics of materials needed for high efficiency thermoelectric conversion will be discussed, and a quick review of the most promising materials currently under development will be given. This review paper will put a particular emphasis on nanostructured silicon, which represents a valid compromise between good thermoelectric properties on one side and material availability, sustainability, technological feasibility on the other side. The most important bottom-up and top-down nanofabrication techniques for large area silicon nanowire arrays, to be used for high efficiency thermoelectric devices, will be presented and discussed.


Journal of Applied Physics | 2006

Fabrication and characterization of silicon nanowires with triangular cross section

Giovanni Pennelli; Massimo Piotto

Fabrication processes for silicon nanowires with triangular cross section are presented. Processes based on high resolution electron beam lithography and anisotropic etching have been developed on silicon on insulator substrates. As shown by numerical simulations, the triangular shape of the wire allows strong reduction of the dimensions by successive oxidation steps. Moreover, it is easy to define a gate on top of the wire that wraps the device and, with the back gate silicon substrate, allows the biasing of the structure on all sides. The conduction through the wire, as a function of the gate bias and for different temperatures, is reported and discussed.


Applied Physics Letters | 1996

Current transport in free-standing porous silicon

Alessandro Diligenti; Andrea Nannini; Giovanni Pennelli; Francesco Pieri

The electrical conduction of free‐standing porous silicon layers, obtained from n+ silicon with various anodization currents and illumination conditions, has been investigated in vacuum as a function of the temperature in the interval 300‐210 K. The two‐contact I‐V characteristic is determined by the metal/porous silicon rectifying interface, whereas, by using the four‐contact technique, a linear dependence of the current vs voltage was found. The resistance of free‐standing samples showed a thermally activated behavior, with activation energies ranging from 0.1 to 0.44 eV. It was found that the activation energy decreased if the light intensity during the anodization was reduced. Variations of activation energy were also observed if the anodization current was changed but, in this case, it was not possible to find any correlation over the parameter range investigated.


Journal of Materials Research | 1997

PULSED LASER DEPOSITION AND CHARACTERIZATION OF CONDUCTIVE RUO2 THIN FILMS

A. Iembo; Francesco Fuso; Ennio Arimondo; C. Ciofi; Giovanni Pennelli; G. M. Curro; F. Neri; M. Allegrini

RuO{sub 2} thin films have been produced on silicon-based substrates by {ital in situ} pulsed laser deposition for the first time. The electrical properties, the surface characteristics, the crystalline structure, and the film-substrate interface of deposited samples have been investigated by 4-probe resistance versus temperature technique, scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy, respectively. The films show good electrical properties. The RuO{sub 2}-substrate interface is very thin ({approx}3 nm), since not degraded by any annealing process. These two characteristics render our films suitable to be used as electrodes in PZT-based capacitors.{copyright} {ital 1997 Materials Research Society.}


IEEE Sensors Journal | 2012

Smart Flow Sensor With On-Chip CMOS Interface Performing Offset and Pressure Effect Compensation

Massimo Piotto; Michele Dei; Federico Butti; Giovanni Pennelli; Paolo Bruschi

A single-chip smart flow sensor based on a thermal principle is presented. The device is fabricated through a commercial complementary metal-oxide-semiconductor (CMOS) process combined with a postprocessing procedure. A configurable electronic interface performing signal reading and nonideality compensation is integrated with the sensing structures on the same chip. The interface implements recently proposed approaches to offset and pressure effect compensation. Detailed experimental results are presented demonstrating correct operation of the proposed microsystem.


Journal of Applied Physics | 2007

Fabrication of silicon nanostructures by geometry controlled oxidation

Giovanni Pennelli; Bruno Pellegrini

This work presents fabrication processes of nanostructures on a top silicon layer of silicon on insulator substrates. These processes rely on the properties shown by a trapezoidal cross section, as the one obtained by anisotropic wet etching, when reduced by dry oxidation. As demonstrated by numerical simulations, oxide stress limits the oxidation process if the minor base is large enough, compared with the thickness. If instead the minor base is small, a triangular section is generated during the oxidation process and a controlled strong reduction of the cross section, until the nanometer range is possible. The fabrication of a silicon nanowire longer than 1.5 μm and with a cross section of 15 nm, obtained with this technique, is shown and demonstrated. By providing zones with different initial cross section dimensions, constrictions can be fabricated in suitable positions and controlled by oxidation reduction, so that tunnel barriers can be obtained. Room temperature electrical characterization of tunne...


Applied Physics Letters | 1995

Improved optical emission of porous silicon with different postanodization processes

Vittorio Pellegrini; Francesco Fuso; Gabriele Lorenzi; M. Allegrini; Alessandro Diligenti; Andrea Nannini; Giovanni Pennelli

Time integrated and time resolved photoluminescence measurements have been performed at room temperature on porous silicon samples prepared under identical conditions but processed after anodization in four different ways. New and simple treatments were made to reduce the structural damage due to the drying process. The results show that suitable conditions exist to substantially improve the optical emission of porous silicon samples. The observed modifications of the time integrated photoluminescence signal are related to dangling bonds produced during the drying process that are supposed to act as trap states in the electron–hole or excitons recombination mechanism. Time resolved measurements provide an evaluation of the relative density of trap states for each analyzed sample.


Review of Scientific Instruments | 2003

A low cost high resolution pattern generator for electron-beam lithography

Giovanni Pennelli; F. D’ Angelo; Massimo Piotto; Giuseppe Barillaro; Bruno Pellegrini

A simple, very low cost pattern generator for electron-beam lithography is presented. When it is applied to a scanning electron microscope, the system allows a high precision positioning of the beam for lithography of very small structures. Patterns are generated by a suitable software implemented on a personal computer, by using very simple functions, allowing an easy development of new writing strategies for a great adaptability to different user necessities. Hardware solutions, as optocouplers and battery supply, have been implemented for reduction of noise and disturbs on the voltages controlling the positioning of the beam.

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